One type of subsea well production utilizes a subsea Christmas tree located at the sea floor at the upper end of the well. The Christmas tree has valves and a choke for controlling the well fluid being produced.
In one type of production, the fluid flows from the tree to a production platform at the surface. The production platform has separators for separating waste products, such as water, from the well fluid. One method to dispose of the separated water is to pump it back down conduits to subsea injection wells. This system requires sufficiently high pressure in the well in order to convey the well fluid, which still contains water, to the production platform. In very deep water, the well pressure may be inadequate. Also, the injection pump must have sufficient capacity to overcome the frictional effects of the conduits leading to the injection wells, which may be remote from the wells being produced.
Installing a subsea separator adjacent a subsea well for separating fluid has been proposed. Also, subsea pumps have been proposed for location on or adjacent wellhead assemblies for boosting the pressure at the wellhead to convey fluids to a floating production vessel.